Defect inspection system

ABSTRACT

A defect inspection system is disclosed for easily setting inspection conditions and providing an inspection condition and a defect signal intensity to an operator. The defect inspection system digitizes a defective image, and a reference image corresponding thereto and a mismatched portion of the defective image and the reference image as a defect signal intensity and accumulates them in association with the inspection condition. The inspection conditions are changed to repeat evaluations while repeating accumulating works until the evaluation of all the inspection conditions in a set range is completed. A recipe file including the accumulated conditions having the high defect signal intensity and an inspection condition item distribution as a inspection condition recipe is automatically outputted and provided to the operator.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of application Ser. No. 12/957,018,filed on Nov. 30, 2012, which is a continuation of application Ser. No.11/501,815, filed on Aug. 10, 2006, now allowed, which claims thebenefit of Japanese patent application No. JP 2005-258664 filed on Sep.7, 2005, the disclosures of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a inspection technique of comparing aninspection image of an object to be inspected obtained by using light,electron beam, or the like and a reference image corresponding theretoand of detecting a defect such as a fine pattern defect or a foreignmaterial occurring on a substrate from a difference between the imagesand, in particular, to a technique effectively applied to a defectinspection system for performing appearance inspection of a substratefor a semiconductor wafer, a photomask, a liquid crystal, or the like.

For example, in a defect inspection apparatus constituting the defectinspection system, a plurality of inspection condition items are presentand the number of combinations thereof is tens or more. Therefore, priorto inspection, work (condition selecting work) is required forperforming an inspection on some inspection conditions and selecting onecondition that has the highest sensitivity of defect detection from theinspected conditions. However, there is such a problem that considerableskill is required to the work because of taking some of trial and errorand further heavy workload is required.

As a method for solving the above problem, for example, techniquesdisclosed in Japanese Patent Laid-open Publication No. 2002-303586 andJapanese Patent No. 3300830 are known. The technique disclosed inJapanese Patent Laid-open Publication No. 2002-303586 allows even anunskilled person to set an inspection condition having high sensitivityof defect detection easily and in a short period of time by: inspectingan object to be inspected on a plurality of test conditions constitutedfrom a plurality of inspection condition items set in advance whileautomatically changing inspection conditions; quantitatively arrangingand displaying images, contrasts, luminance distributions, and the likeon respective test conditions; performing automaticdefect/misinformation discrimination based on the test inspectionresult; displaying the classification result on a map, and selecting thecondition having a low misinformation ratio.

The technique disclosed in Japanese Patent No. 3300830 provides a methodof comparing information about a defect detected on a defect inspectionapparatus with data extracted from distribution of scattering light froma defect obtained according to simulation to classify the detecteddefects according to sizes and shapes, thereby making it possible todetect presence or absence of a defect such as a foreign material on asubstrate, on a surface of which a pattern is formed, and further detectthe size or shape of the defect rapidly and easily if the defect ispresent.

However, in the technique disclosed in Japanese Patent Laid-openPublication No. 2002-303586, a whole wafer is inspected while changingthe inspection conditions and defect maps are arranged and displayed forthe respective conditions, so that it is necessary to inspect the entirewafer by the number of inspection conditions. For example, when thetechnique is applied to an inspection apparatus whose throughput is nothigh, there is such a problem that an unrealistically long priorevaluation time is necessary. In addition, a sample that is an object tobe inspected is required for setting an inspection condition.

Also, the technique disclosed in Japanese Patent No. 3300830 provides amethod for classifying the simulation results according to the sizes andshapes of the defects. The method is useful for classifying the defects,but does not assist in setting of the inspection condition.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a defect inspectionsystem which can perform inspection condition setting easily and in arelatively short period of time, make an examination of the inspectioncondition setting even if there is no sample, and further provide aninspection condition and a defect signal intensity to a person, who setsan inspection condition, to assist in the inspection condition setting.

Outlines of representative ones of the inventions disclosed in thepresent application will be briefly described as follows.

The present invention is configured as a system comprising means havingthe following respective functions, for the purpose of semi-automationof condition setting of a defect inspection system which detects adefect by comparing an inspection image of an object to be inspected anda reference image: (1) a function of accumulating the inspection imageand the reference image in association with the inspection condition;(2) a function of digitalizing, as a defect signal intensity, amismatched portion of the inspection image and the reference image ofthe item (1) to accumulate the defect signal intensity in associationwith the inspection condition; (3) a function of changing the inspectionconditions to repeat the accumulating works of the items (1) and (2)until evaluation on all the inspection conditions in a set range iscompleted; (4) a function of repeating the items (1) to (3) by thenumber of kinds of defects when a plurality of defects to be inspectedare present; and (5) a function of automatically outputting, as aninspection condition recipe, a recipe file including the accumulatedconditions having the high defect signal intensity and an inspectioncondition item distribution or of expressly providing the recipe file toa worker who performs the inspection condition setting.

Effects obtained from representative ones of the inventions disclosed inthe present application will be briefly described as follows.

According to the present invention, in the condition setting of thedefect inspection system which detects the defect by comparing theinspection image of the object to be inspected and the reference image,the inspection condition setting can be performed easily and in arelatively short period of time. It is possible to examine theinspection condition setting even when there is no sample. Further, thepresent invention provides a function capable of providing theinspection conditions and the defect signal intensities to a person, whosets the inspection condition, to assist in the inspection conditionsetting.

Those and other objects, features, and advantages of the invention willbe apparent from the following more particular description of preferredembodiments of the invention, as illustrated in the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram for explaining a concept of an operation flow of adefect inspection system in an embodiment of the present invention;

FIG. 2 is a diagram for explaining one example of a configuration of adefect inspection system in a first embodiment of the present invention;

FIG. 3 is a diagram for explaining one example of outline of operationlogic of the defect inspection system in the first embodiment of thepresent invention;

FIG. 4 is a diagram for explaining one example of an operation flow ofthe defect inspection system in the first embodiment of the presentinvention;

FIG. 5 is a diagram for explaining constituent elements of an image DBand one example of a DB producing method in the defect inspection systemin the first embodiment of the present invention;

FIG. 6 is a diagram for explaining one example of defect informationcomprising an image including a defect, a reference image, and a defectsignal image produced from the both images in the first embodiment ofthe present invention;

FIG. 7A is a diagram for explaining a defect-coordinate specifyingassistance screen in the first embodiment of the present invention andfor showing a wafer map, a review image, and a coordinate inputtingportion where coordinates on the review image are inputted;

FIG. 7B is a diagram for explaining a defect-coordinate specifyingassistance screen in the first embodiment of the present invention andfor showing an example of displaying a wafer map and an input portionthrough which an inspection image acquisition condition is inputted;

FIG. 8 is a diagram for explaining one example of a configuration of adefect inspection system in a second embodiment of the presentinvention;

FIG. 9 is a diagram for explaining one example of an operation flow ofthe defect inspection system in the second embodiment of the presentinvention;

FIG. 10 is a diagram for explaining one example of a simulation modelobtained by modeling a defect and its vicinity in the second embodimentof the present invention;

FIG. 11 is a diagram for explaining one example of a constitution of adefect inspection system in a third embodiment of the present invention;

FIG. 12 is a diagram for explaining one example of an operation flow ofthe defect inspection system in the third embodiment of the presentinvention;

FIG. 13 is a diagram for explaining one example of a display of a defectsignal intensity distribution and a user interface concerning thedisplay of the distribution in the third embodiment of the presentinvention;

FIG. 14A is a diagram for explaining one example of coordination with adisplay screen of a defect signal intensity distribution and recipeproducing software;

FIG. 14B is a diagram for explaining one example of coordination with awafer map and the recipe producing software in the third embodiment ofthe present invention;

FIG. 15 is a diagram for explaining one example of an operation flow ofa defect inspection system in a fourth embodiment of the presentinvention.

FIG. 16 is a diagram for explaining one example of two kinds of defects,two kinds of images, and a defect signal in the fourth embodiment of thepresent invention;

FIG. 17 is a diagram for explaining one example of a user interface forselecting the kind of the defect when a defect signal intensitydistribution is displayed in the fourth embodiment of the presentinvention; and

FIG. 18A is a diagram for explaining one example of a user interface fordisplaying the signal intensity distribution of two kinds of defects inthe fourth embodiment of the present invention; and

FIG. 18B is a diagram explaining one example of coordination with awafer map showing a distribution of two kinds of defects on a wafer andwith recipe producing software.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will be explained below in detailwith reference to the drawings. Incidentally, throughout all figures forexplaining the embodiments, the same reference numerals are in principledenoted by the same members and repetitive explanation thereof isomitted.

Concept of Embodiments of the Invention

Concept of embodiments of the present invention will be explained withreference to FIG. 1. FIG. 1 is a diagram for explaining a concept of anoperation flow of a defect inspection system.

A defect inspection system according to the embodiments of the presentinvention has functions of performing the following operations.

In operations of the defect inspection system according to theembodiments of the present invention, as shown in FIG. 1, an image(called also “defective image”) including a defect and its vicinity,which is an inspection image, and a reference image are firstaccumulated in association with an inspection condition (S1). Further, amismatched portion of the defective image and the reference image isdigitalized as a defect signal intensity and is accumulated inassociation with the inspection condition (S2). Whether evaluation ofall the inspection conditions in a set range is completed is determined(S3), and the evaluation is repeated while changing the inspectionconditions and repeating the accumulating works of S1 and S2 until allthe evaluations are completed (S4). When a result of determination at S3indicates that all the evaluations have been completed, whether therepeat is performed by the number of defects to be inspected isdetermined (S5). When the result of the determination at S5 indicatesthat there are a plurality of defects to be inspected, the works at S1to S4 are repeated by the number of kinds of the defects (S6). Whenthere are not a plurality of defects to be inspected, a recipe fileincluding an accumulated condition having a high defect signal intensityand an inspection condition item distribution is automatically outputtedas an inspection condition recipe to expressly provide the same to aworker who sets the inspection condition (S7). Appearance inspection ofdetecting a pattern defect or a foreign material on a substrate isperformed (58). The appearance inspection is performed to asemiconductor wafer, a photomask, a liquid crystal, or the like.

Also, in the defect inspection system according to the embodiments ofthe present invention, when the defective image and the reference imageare acquired, there are the following methods as detailed below: (1) amethod for using an inspection apparatus which can specify coordinatesof a defect present on a substrate in setting an inspection condition,can load an inspection condition recipe file produced in the outside,has a function of outputting a defective image and its reference imagewhen the coordinates of the defect is specified on the recipe, andobtain, as a defective image and its reference image, images outputtedby the inspection apparatus; and (2) a method for producing a simulationmodel based on a structural drawing of a substrate to be inspected,calculating the case where a defect is present and the case where nodefect is present according to simulation based on a defect inspectionmethod using a means for realizing the operations shown in FIG. 1, andobtaining the defective image and its reference image.

Further, when the mismatched portion of the inspection image and thereference image is digitalized as a defect signal intensity, there arethe following methods as detailed later: (1) a method for using adifference image between the inspection image and its reference image;(2) a method for using an indicator of defect determination in aninspection apparatus having a means for realizing the operations shownin FIG. 1; (3) a method for using an inspection apparatus which canspecify coordinates of a defect existing on the substrate in setting theinspection condition, can load an inspection condition recipe fileproduced in the outside, has a function of outputting a defectdetermination image when the coordinates of a defect is specified on therecipe, and define brightness of the image outputted by the inspectionapparatus as a defect signal intensity.

Each embodiment based on the concept of the embodiments of the presentinvention will be detailed below.

First Embodiment

A first embodiment of the present invention will be explained withreference to FIG. 2 to FIG. 7B. FIG. 2 is a diagram for explaining oneexample of a configuration of a defect inspection system; FIG. 3 is adiagram for explaining one example of schematic operation logic of thedefect inspection system; FIG. 4 is a diagram for explaining one exampleof an operation flow of the defect inspection system; FIG. 5 is adiagram for explaining a constituent element of an image DB and oneexample of a DB producing method in the defect inspection system; FIG. 6is a diagram for explaining one example of defect information comprisingan image including a defect, a reference image, and a defect signalimage produced from both images; and FIGS. 7A and 7B are diagrams forexplaining a defect-coordinate specifying assistance screen.

As shown in FIG. 2, a defect inspection system 100 according to thepresent embodiment comprises: an inspection apparatus 1000; a defectsignal DB producing system 1100 depending on defects to be detected; adefect signal intensity calculating system 1110, an inspection image DB1120, and a defect signal DB 1130 included in the defect signal DBproducing system 1100; a recipe producing system 1200; and the like,wherein they are connected mutually via a local area network (LAN).

As shown in FIG. 3, in the operation logic of the defect inspectionsystem, a DB associated with an inspection image acquisition conditionand having, as constituent elements, an inspection image including adefect and a reference image, is first produced (S11). In the operation,as shown in FIG. 5, there is produced the inspection image DB 1120 whichincludes, as a constituent element 1127, an inspection image acquisitioncondition 1121, a defect kind information 1119, a defect inspectionimage 1122 obtained by imaging the vicinity of defect coordinates 1123,and an inspection image 1126 at coordinates of an adjacent die 1128corresponding to the defect coordinates 1123. Here, the inspection imageacquisition condition 1121 is an item which affects the defectinspection image 1122 among parameters which can be changed on a recipeof the inspection apparatus 1000. Though the defect coordinates 1123where a defect to be detected 90 is present may be checked in advance,if the inspection apparatus includes a function capable of specifyingcoordinates in detail using a wafer review screen as shown in FIGS. 7Aand 7B, the function may be used.

A defect-generated signal intensity is calculated from the inspectionimage including a defect and the inspection image including no defect,and a DB including, as a constituent element, the signal intensityassociated with the inspection image acquisition condition is produced(S12). Further, a defect signal intensity distribution in an area ofinspection image acquisition condition items is displayed (S13). Aninspection image acquisition condition is selected on a display screenof the defect signal intensity distribution and reflected on a recipeparameter (S14) to output a new recipe (S15).

In FIG. 4, the inspection apparatus 1000 has a function of outputtingthe defect inspection image 1122 in the vicinity of the defectcoordinates 1123 specified on an inspection recipe and the inspectionimage 1126 in the vicinity of the coordinates 1128 of the adjacent diecorresponding to the defect coordinates 1123, and a function of remotelyloading a recipe file produced in the outside and performing inspection.

A producing method of the constituent element 1127 of the inspectionimage DB 1120 will be explained with reference to FIG. 4. First,parameters which do not contribute to an inspection image acquisitioncondition, such as a wafer map and an inspection region, are set in therecipe producing system 1200. Next, a set range of the inspection imageacquisition conditions is specified. Thereby, the recipe producingsystem 1200 produces a temporary inspection recipe 1260 in which theinspection image acquisition conditions are changed in the set range.

At this time, in the temporary inspection recipe 1260, the defectcoordinates are specified, and setting is made to output the defectinspection image 1122 and the inspection image 1126. The temporaryinspection recipe 1260 is remotely loaded by the inspection apparatus1000 to perform inspection, thereby acquiring the defect inspectionimage 1122 and the inspection image 1126. The producing of theconstituent elements is repeated while changing the inspection imageacquisition conditions 1121 within a changeable range on the recipe ofthe inspection apparatus 1000.

Next, a defect signal intensity 1131 is calculated from the constituentelement 1127 of the inspection image DB 1120 by the defect signalintensity calculating system 1110, and the defect signal intensity 1131and the inspection image acquisition condition 1121 are stored in thedefect signal DB 1130 in association with each other via a convertingmeans. The producing procedure of the constituent element of the defectsignal DB 1130 is performed repeatedly regarding all the constituentelements in the inspection image DB 1120.

Next, in the defect signal intensity calculating system 1110, aconstituent element 1139 having the highest defect signal intensity isselected from the constituent elements in the defect signal DB 1130 viaan extracting means and, at that time, a defect signal maximum conditionparameter file 1140 reflecting the inspection image acquisitioncondition 1129 is outputted.

For example, a method for calculating the defect signal intensity 1131from the constituent element 1127 in the inspection image DB 1120 by thedefect signal intensity calculating system 1110 includes subtracting theinspection image 1126 from the defect inspection image 1122 to produce adifference image 1141 and setting, as a defect signal intensity 1131, avalue of a pixel having the maximum absolute value on the differenceimage 1141, as shown in FIG. 6.

Next, in the recipe producing system 1200, prior to outputting of aninspection recipe file, a user sets a parameter contributing to noinspection image acquisition conditions, such as a wafer map or aninspection region, selects the defect signal maximum condition parameterfile 1140 for writing at a time of setting of the inspection imageacquisition conditions, and properly modifies and determines the setparameter to output a new recipe 1300 after updating the inspectionimage acquisition condition. The new recipe 1300 is loaded into theinspection apparatus 1000 and used as a new inspection recipe.

Note that, as to the defect signal intensity 1131, a method for using asignal value calculated based on defect detection algorithm which isused when defect detection is determined in the inspection apparatus1000 may be used. When there are a plurality of options in the defectdetection algorithm, the defect signal intensity 1131 may be handled inthe same way as the other inspection condition items by calculating thedefect signal intensity 1131 for each algorithm. Further, the recipeproducing system 1200 may have a function of succeeding and setting aparameter which does not contribute to the inspection image acquisitioncondition by loading a pre-produced recipe.

Second Embodiment

A second embodiment of the present invention will be explained withreference to FIG. 8 to FIG. 10. FIG. 8 is a diagram for explaining oneexample of a configuration of a defect inspection system; FIG. 9 is adiagram for explaining one example of an operation flow of the defectinspection system; and FIG. 10 is a diagram for explaining one exampleof a simulation model obtained by modeling a defect and its vicinity.

As shown in FIG. 8, a defect inspection system 100 a of the secondembodiment comprises: an inspection apparatus 1000; a defect signal DBproducing system 1100, a defect signal intensity calculating system1110, an inspection image DB 1120, and a defect signal DB 1130 includedin the defect signal DB producing system 1100; a recipe producing system1200; an inspection image simulation system 1500; and a structure DB1510, a material DB 1520, a result DB 1550 for accumulating simulationresults, and an inspection image simulator 1560 included in theinspection image simulation system 1500; and the like, whereby they areconnected mutually via a local area network (LPN).

Operations of the defect inspection system will be explained withreference to FIG. 9. Prior to the operations of the defect inspectionsystem, as shown in FIG. 10, information 1551 about a defect 90 to bedetected is taken out of the result DB 1550 in which simulation resultsof a process simulator are accumulated, a structure of a sample 1501 inthe vicinity of the defect 90 is taken out of the material DB 1510, aconstant of a material used in the structure of the sample 1501 is takenout of the structure DB 1520, and a simulation model 1580 of ainspection image including a defect and a simulation model 1581 of aninspection image including no defect are produced from the structure,the material, and the information about the defect.

Next, as shown in FIG. 9, the defect inspection image 1122 and theinspection image 1126, which are the constituent elements 1127 in theinspection image DB 1120, are respectively calculated by the inspectionimage simulator 1560 using the models 1580 and 1581. Image simulation isrepeatedly performed while changing the inspection image acquisitioncondition 1121.

Next, the defect signal intensity 1131 is calculated from theconstituent element 1127 in the inspection image DB 1120 by the defectsignal intensity calculating system 1110, and the defect signalintensity 1131 and the inspection image acquisition condition 1121 arestored in the defect signal DB 1130 in association with each other viaan image-to-defect signal intensity converting means. The producingprocedure of a constituent element in the defect signal DB 1130 isperformed repeatedly regarding all the constituent elements of theinspection image DB 1120.

Next, in the defect signal intensity calculating system 1110, theconstituent element 1139 having the highest defect signal intensityamong the constituent elements in the defect signal DB 1130 is selectedvia a defect signal maximum intensity inspection condition extractingmeans, and a defect signal maximum condition parameter file 1140reflecting the inspection image acquisition condition 1129 is outputtedat that time.

For example, a method for calculating the defect signal intensity 1131from the constituent element 1127 in the inspection image DB 1120 by thedefect signal intensity calculating system 1110 includes, like the firstembodiment (FIG. 6), subtracting the inspection image 1126 from thedefect inspection image 1122 to produce a difference image 1141 andsetting, as the defect signal intensity 1131, a value of a pixel havingthe maximum absolute value on the difference image 1141.

Next, in the recipe producing system 1200, prior to outputting ainspection recipe file, a user sets a parameter contributing to noinspection image acquisition conditions, such as a wafer map or aninspection region, selects the defect signal maximum condition parameterfile 1140 for writing at the time of setting the inspection imageacquisition condition, and properly modifies and determines a settingparameter to output a new recipe 1300 after updating the inspectionimage acquisition condition. The new recipe 1300 is loaded into theinspection apparatus 1000 and used as a new inspection recipe.

Note that, as to the defect signal intensity 1131, a method for using asignal value calculated based on defect detection algorithm which isused when defect detection is determined in the inspection apparatus1000 may be used. When there are a plurality of options in the defectdetection algorithm, the defect signal intensity 1131 may be handled inthe same way as the other inspection condition items by calculating thedefect signal intensity 1131 for each algorithm. Further, the recipeproducing system 1200 may have a function of succeeding and setting aparameter which does not contribute to the inspection image acquisitioncondition by loading a pre-produced recipe.

Third Embodiment

A third embodiment of the present invention will be explained withreference to FIG. 11 to FIG. 14B. FIG. 11 is a diagram for explainingone example of a constitution of a defect inspection system; FIG. 12 isa diagram for explaining one example of an operation flow of theinspection system; FIG. 13 is a diagram for explaining one example ofdisplay of a defect signal intensity distribution and a user interfaceconcerning the display of the distribution; and FIGS. 14A and 14B arediagrams for explaining one example of coordination with a displayscreen of a defect signal intensity distribution and recipe producingsoftware.

As shown in FIG. 11, a defect inspection system 100 b of the presentembodiment includes: an inspection apparatus 1000; a defect signal DBproducing system 1100; a defect signal intensity calculating system1110, an inspection image DB 1120, and a defect signal DB 1130 includedin the defect signal DB producing system 1100; a recipe producing system1200; a defect signal distribution displaying system 1250; an inspectionimage simulation system 1500; a structure DB 1510, a material DB 1520, aresult DB 1550, and an inspection image simulator 1560 included in theinspection image simulation system 1500; and the like, wherein they areconnected mutually via a local area network (LAN).

Operations of the defect inspection system will be explained withreference to FIG. 12. The inspection image DB 1120, which is associatedwith an inspection image acquisition condition 1121, an informationabout the kind of a defect 1119, a defect inspection image 1122 obtainedby imaging the vicinity of defect coordinates 1123, and an inspectionimage 1126 at coordinates of an adjacent die 1128 corresponding to thedefect coordinates 1123 and which is included as a constituent element1127, is first produced like the first embodiment (FIG. 5).

At this time, the inspection image acquisition condition 1121 is an itemaffecting the defect inspection image 1122 among parameters capable ofchanging on a, recipe of the inspection apparatus 1000, and theproducing of the above-mentioned constituent element is repeated whilechanging the inspection image acquisition condition 1121 within achangeable range on the recipe of the inspection apparatus 1000.

Next, a defect signal intensity 1131 is calculated from the constituentelement 1127 in the inspection image DB 1120 by the defect signalintensity calculating system 1110, and the defect signal intensity 1131and the inspection image acquisition condition 1121 are stored in thedefect signal DB 1130 in association with each other via a convertingmeans. The producing procedure of the constituent element in the defectsignal DB 1130 is performed repeatedly regarding all the constituentelements in the inspection image DB 1120.

For example, the method for calculating the defect signal intensity 1131from the constituent element 1127 of the inspection image DB 1120 by thedefect signal intensity calculating system 1110 may be, like the firstembodiment (FIG. 6), a method for subtracting the inspection image 1126from the defect inspection image 1122 to produce a difference image 1141and setting, as the defect signal intensity 1131, a value of a pixelhaving the maximum absolute value on the different image 1141, or amethod for using a signal value based on defect detection algorithmwhich is used when defect detection is determined in the inspectionapparatus 1000. At this time, information about a size, a shape, or thelike of the defect may be included in the constituent element 1127.

Next, a defect signal intensity distribution map 1151 in an item area ofan inspection image acquisition condition as shown in FIG. 13 isdisplayed using elements of the defect signal DB 1130 via an inspectionimage acquisition condition displaying means and a DOI signaldistribution displaying means. An axis on the display may be set as anitem of the inspection image acquisition condition which affects adefect signal intensity most significantly, or be displayed using anaxis after axis conversion, or be an arbitrary axis which is selected bya person who produces a recipe. Alternatively, two-dimensional displaymay be used, or pseudo three-dimensional display may be used.

As shown in FIG. 13, a user interface is provided on the display screenof the defect signal intensity distribution map in order for the personwho produces a recipe to arbitrarily select an axis of the graph. Aslider for displaying a section in multidimensional space while finelyadjusting a parameter may be provided to the user interface.

As shown in FIGS. 14A and 14B, recipe producing software coordinateswith software having a function of displaying the defect signalintensity distribution map 1151 in the item area of the above-mentionedinspection image acquisition condition, and places a pointer 1152 suchas a mouse on an arbitrary point on the distribution map 1151.Therefore, if the person who produces a recipe executes a positionspecifying operation such as click operation, a parameter of each itemin the inspection image acquisition condition is automatically selectedfrom corresponding coordinates via an inspection image acquisitioncondition selecting means, so that the inspection condition is reflectedon the inspection image acquisition condition on the recipe producingsoftware via a recipe parameter updating means.

Next, in the recipe producing system 1200, a parameter that does notcontribute to the inspection image acquisition conditions such as awafer map or an inspection region is set in advance, and a user properlymodifies and determines the set parameter to output a new recipe 1300.The new recipe 1300 is loaded into the inspection apparatus 1000 andused as a new inspection recipe.

Note that although the present embodiment does not clearly indicate amethod for acquiring the defect inspection image 1122 and the inspectionimage 1126 which are the constituent elements 1127 in the inspectionimage DB 1120, like the above-mentioned first embodiment, the inspectionimage may be acquired in the inspection apparatus 1000 or calculated bysimulation.

Also, the present embodiment does not make any description of the casewhere any problem occurs at a time of performing inspection using thenew recipe 1300 by the inspection apparatus 1000 and anther inspectionrecipe must be further produced accordingly. However, even in this case,since the inspection image DB 1120 and the defect signal DB 1130 arealready present, assistance for producing a recipe becomes possible byimmediately displaying the defect signal intensity distribution map1151, which, needless to say, results in reduction of time for trial anderror and in fine adjustment of the inspection condition necessary forproducing a recipe.

Fourth Embodiment

A fourth embodiment (modification of the third embodiment) of thepresent invention will be explained with reference to FIG. 15 to FIG.18B. FIG. 15 is a diagram for explaining one example of an operationflow of the inspection system; FIG. 16 is a diagram for explaining oneexample of two kinds of defects, two kinds of images, and a defectsignal; FIG. 17 is a diagram for explaining one example of a userinterface for selecting a kind of the defect when a defect signalintensity distribution is displayed; and FIGS. 18A and 18B are diagramsfor explaining a concept of displaying a signal intensity distributionof two kinds of defects and one example of a user interface associatedwith the concept.

For example, if an inspection image acquisition condition is set byfocusing on a signal intensity of a specific kind of defect when aplurality of defects are present on a wafer processed in one step, itmay occur that a signal intensity of another kind of defect becomes lowand necessary defect sensitivity cannot be secured. In response to this,there is the case where a recipe must be produced by setting aninspection image acquisition condition for obtaining signal intensitiesof a plurality of kinds of defects equal to or more than constant valueseven if signal intensities becomes low in some degree. To such a case,the present embodiment is applied.

Processing procedure for assisting to produce a recipe in operations ofthe defect inspection system will be explained with reference to FIG.15. Here, the case of setting an inspection image acquisition conditioncorresponding to two kinds of defects will be explained.

As to two kinds of defects (a defect 1 and a defect 2), a defect signalintensity relating to the defect 1 and a defect signal intensityrelating to the defect 2 are stored together with the information aboutthe kind of a defect 1119 in the defect signal DB 1130 in advance.

An outline of an object of the present embodiment will be explained withreference to FIG. 16. The defect signal intensity 1131 of the defect 1is calculated using defect information 1912 including a defectinspection image 1122, a reference image (inspection image 1126), and adefect detection signal. The defect signal intensity 1731 of the defect2 is calculated using defect information 1922 including a defectinspection image 1722, a reference image (inspection image 1726), and adefect detection signal.

In a distribution map in FIG. 16, an example of a defect detectionsignal intensity distribution 1911 of the defect 1 and a defectdetection signal intensity distribution 1921 of the defect 2 whenmeasurement conditions 1 to 4 are changed is simultaneously plotted in afour-dimensional space whose axes are defined by the measurementconditions 1 to 4. When the number of measurement conditions is “n”, thedistributions 1911 and 1921 are expressed as a distribution in annth-dimensional space.

The present embodiment provides a means of displaying the defectdetection signal intensity distributions 1911 and 1921 on a screen toindicates an effectiveness of overlapping 1903 of both distributions toa person who produces an inspection recipe, thereby providinginformation for making a determination about whether a signal intensityenough to detect two kinds of defects one time is obtained and providingan interface for selecting such a measurement condition “A” that theperson who produces an inspection recipe can obtain sufficiently thesignal intensity and for reflecting the same on an inspection recipe.

Next, the person who produces an inspection recipe selects, as shown inFIG. 17, two kinds of defects 90 intended to display the defect signalintensity distributions, namely, the defect 1 and the defect 2 by thedefect signal distribution displaying system 1250. Thereby, as shown inFIGS. 18A and 18B, the defect signal intensity distribution map 1151 inwhich two kinds of defect signal intensity distributions 1911 and 1921stored in the defect signal DB 1130 are plotted on the same graph isdisplayed on a screen such as a CRT.

Here, the axis on the display may be set as an item of the inspectionimage acquisition condition which affects the defect signal intensitymost significantly, or be displayed using an axis after axis conversion,or be an arbitrary axis selected by the person who produces a recipe.Alternatively, two-dimensional display may be used, or pseudothree-dimensional display may be used. Also, a user interface for theperson who produces a recipe to arbitrarily select an axis of the abovegraph is provided on the display screen of the above defect signalintensity distribution map.

Like the third embodiment, recipe producing software coordinates withsoftware having a function of displaying the defect signal intensitydistribution map 1151 in the item area of the above inspection imageacquisition condition, and places a pointer 1152 such as a mouse on anarbitrary point on the above distribution map 1151. Therefore, when theperson who produces a recipe performs a position specifying operationsuch as a click operation, a parameter of each item of an inspectionimage acquisition condition is automatically selected from correspondingcoordinates and the inspection condition is reflected to an inspectionimage acquisition condition on the recipe producing software.

Subsequently, a new recipe 1300 is outputted by an acceptance/outputtingoperation from the person who produces a recipe. The new recipe 1300 isloaded into the inspection apparatus 1000 and used as a new inspectionrecipe.

Note that the present embodiment has described the case where two kindsof defects are present on the same wafer. However, if there is theconstituent element 1127 of the inspection image DB 1120 associated withthe inspection image acquisition condition 1121, the defect kindinformation 1119, the defect inspection image 1122 obtained by imagingthe vicinity of defect coordinates 1123, and the inspection image 1126at coordinates of the adjacent die 1128 corresponding to the defectcoordinates 1123, then the defect inspection can be performed withoutlimiting the number of kinds of defects to two.

As explained above, according to each embodiment, in condition settingof the defect inspection system for detecting the defect by comparingthe inspection image of the object to be inspected and the referenceimage, the inspection condition setting can be performed easily in arelatively short period of time. It becomes possible to examine theinspection condition setting even when there is no sample. Further, byproviding an inspection condition and a defect signal intensity to theperson who sets the inspection condition, a function of assisting in theinspection condition setting can be provided.

The invention made by the present inventors is specifically explainedbased on the embodiments. However, the present invention is not limitedto the above-mentioned embodiments and, needless to say, can bevariously modified and altered within the scope of not departing fromthe gist thereof.

The present invention relates to a inspection technique of comparing aninspection image of an object to be inspected obtained by using light,electron beam, or the like and a reference image and of detecting adefect such as a fine pattern defect or a foreign material occurring ona substrate from a difference between the images and, in particular, iseffectively applicable to a defect inspection system for performingappearance inspection of a substrate for a semiconductor wafer, aphotomask, a liquid crystal, or the like.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiment is therefore to be considered in all respects as illustrativeand not restrictive, the scope of the invention being indicated by theappended claims rather than by the foregoing description and all changeswhich come within the meaning and range of equivalency of the claims aretherefore intended to be embraced therein.

What is claimed is:
 1. A defect inspection method comprising steps of:an irradiation step of irradiating light to a sample; a detection stepof detecting scattered light from the sample which is irradiated in theirradiation step; a process step of producing a two dimensional defectsignal intensity distribution map having two axes by using a pixel valueof a different image between an inspection image and a reference imagewhich is obtained by processing the scattered light detected in thedetection step; and an inspection-recipe determination step ofdetermining an inspection recipe by using the defect signal intensitydistribution map which is produced in the process step, wherein bothaxes of the defect signal intensity distribution map which is producedin the process step are inspection condition items of the inspectionrecipe which affect the inspection image.
 2. The defect inspectionmethod according to claim 1, wherein an item of one of the axis of thedefect signal intensity distribution map which is produced in theprocess step is set.
 3. The defect inspection method according to claim1, wherein the defect inspection method further includes a display stepof displaying the defect signal intensity distribution map which isproduced in the process step.
 4. The defect inspection method accordingto claim 1, wherein the defect signal intensity distribution map whichis displayed in a display step is displayed with a contrastcorresponding to a magnitude of a defect signal intensity.
 5. The defectinspection method according to claim 1, wherein the defect inspectionmethod further includes a selection step of selecting an arbitralposition of the defect signal intensity distribution map which isdisplayed in a display step and setting a parameter of an inspectionrecipe for the position selected.
 6. The defect inspection methodaccording to claim 1, wherein, in a display step, a plurality of defectsignal intensity distribution maps respectively corresponding to aplurality of defects are displayed.
 7. The defect inspection methodaccording to claim 1, wherein the defect signal intensity distributionmap which is produced in the process step is a plurality of defectsignal intensity distribution maps respectively corresponding to aplurality of defects.
 8. The defect inspection method according to claim7, wherein, in the inspection-recipe determination step, an inspectionrecipe is determined in accordance with a degree of overlapping amongthe plurality of defect signal intensity distribution maps.
 9. A defectinspection apparatus comprising: an inspection device configured toirradiate light to a sample; a detector configured to detect scatteredlight from the sample which is irradiated by the inspection device; aprocessor configured to produce a two dimensional defect signalintensity distribution map having two axes by using a pixel value of adifferent image between an inspection image and a reference image whichis obtained by processing the scattered light detected by the detector;and an inspection-recipe determination device configured to determine aninspection recipe by using the defect signal intensity distribution mapwhich is produced in the processor step, wherein both axes of the defectsignal intensity distribution map which is produced by the processorstep are inspection condition items of the inspection recipe whichaffect the inspection image.
 10. The defect inspection apparatusaccording to claim 9, wherein an item of one of the axis of the defectsignal intensity distribution map which is produced by the processor isset.
 11. The defect inspection apparatus according to claim 9, whereinthe defect inspection apparatus further includes a display deviceconfigured to display the defect signal intensity distribution map whichis produced by the processor.
 12. The defect inspection apparatusaccording to claim 11, wherein the defect signal intensity distributionmap which is displayed by the display device is displayed with acontrast corresponding to a magnitude of a defect signal intensity. 13.The defect inspection apparatus according to claim 11, wherein thedefect inspection apparatus further includes a selection deviceconfigured to select an arbitral position of the defect signal intensitydistribution map which is displayed by the display device and to set aparameter of an inspection recipe for the position selected.
 14. Thedefect inspection apparatus according to claim 9, wherein, in a displaydevice, a plurality of defect signal intensity distribution mapsrespectively corresponding to a plurality of defects are displayed. 15.The defect inspection apparatus according to claim 9, wherein the defectsignal intensity distribution map which is produced by the processor isa plurality of defect signal intensity distribution maps respectivelycorresponding to a plurality of defects.
 16. The defect inspectionapparatus according to claim 15, wherein, in the inspection-recipedetermination device, an inspection recipe is determined in accordancewith a degree of overlapping among the plurality of defect signalintensity distribution maps.